The objective of this project is to examine cancer incidence and mortality among populations exposed to ionizing and non-ionizing radiation, especially low-dose levels. As pressure mounted to identify the health effects of low-level radiation, a Radiation Studies Section was organized and large-scale studies of irradiated populations initiated. Groups studied include 80,000 Japanese A-bomb survivors, over 100,000 cervical cancer patients treated with radium implants, 20,000 former tuberculosis patients who received multiple chest fluoroscopies, 3,500 children exposed to head and neck irradiation, other patients exposed to diagnostic and therapeutic radiation, workers with histories of occupational exposures to radiation, and the populations of SEER reporting areas with different levels of solar UV radiation. In addition, project members have served on committees and task forces of DHEW, EPA, DOE, NIH, and NCI formulating government responses to current problems associated with health effects of ionizing radiation.